This invention relates generally to enhancing the accuracy of measurements of a physical quantity and more particularly to a method and system for enhancing the accuracy of measurements of a physical quantity.
Modeling of a physical object often requires the taking of measurements. The measurement taking process on occasion introduces an error associated with each measured value. If the measurement taking process is conducted in an appropriate fashion, the errors should be normally distributed about a mean of zero. However, at times, the measurement taking or measurement recordation process is flawed, resulting in flawed or anomalous data. In such a case the use of such data to represent the measured object would be incorrect and would provide imprecise results. Therefore, it is desirable to determine whether a measurement is anomalous before using the measurement to represent a physical quantity.
Although anomaly detection has utility in numerous applications and for numerous types of measurements, one example of the usefulness of anomaly detection will be described with reference to bathymetric data. Oceanographers and ocean explorers make use of charts of the ocean floors. Such charts are produced by taking depth measurements of the ocean floor. One example of a procedure for taking a depth measurement of the ocean floor involves projecting, from an ocean vessel, sound waves to the bottom of the ocean floor and measuring the time required for a reflected wave to return to the vessel. Such a procedure is subject to a variety of sources of error that create anomalous measurements. For example, a large ocean animal, such as a whale, may reflect a portion of the sound wave back to the vessel, creating an anomalous reading. In addition, measurements may be improperly recorded in meters where feet is the appropriate unit of measure, or feet where meters are the appropriate unit of measure. Such sources of errors lead to anomalous measurements that should be discarded prior to utilizing the data to represent a physical quantity.
Accordingly, a need has arisen for an improved method and system for enhancing the accuracy of measurements of a physical quantity. The present invention provides a system and method for enhancing the accuracy of measurements representing a physical quantity.
According to one embodiment of the invention, a method for enhancing the accuracy of measurements representing a physical quantity includes determining a trend for a plurality of measurements. For each of at least one of the plurality of measurements an associated residual between the trend and the measurement is determined, and, for at least one of the associated residuals, there is determined an interpolated value for the residual. The method also includes comparing, for each of the at least one associated residuals, the residual to the interpolated value of the residual to determine whether a measurement associated with the residual is anomalous. In response to determining that a measurement associated with the residual is anomalous, the anomalous measurement is discarded. The remaining non-anomalous measurements then represent the physical quantity.
According to another embodiment of the invention, a system for enhancing the accuracy of measurements of a physical quantity includes a storage medium, a processor coupled to the storage medium, and a computer program stored in the storage medium. The processor executes the computer program to determine a trend for a plurality of measurements. The processor executing the computer program generates a determination, for each of at least one of the plurality of measurements, an associated residual between the trend and the measurement, and also determines, for each of at least one of the associated residuals, an interpolated value for the residual. The processor running the computer program also compares, for each of the at least one associated residuals, the interpolated value to the residual to determine whether a measurement associated with the residual is anomalous. In response to determining whether a measurement is anomalous, execution of the computer program generates an indication that the measurement is anomalous so that it may be discarded. The non-anomalous measurements are then output from the system.
Embodiments of the invention provide numerous technical advantages. For example, in one embodiment of the invention, a method for enhancing the accuracy of measurements allows determination of whether a measurement is anomalous and whether it may be discarded. Discarding anomalous measurements creates a more accurate representation of the measured object than if the anomalous measurements were included. In one embodiment of the invention a Kriging process is utilized to perform an interpolation used in determining if a measurement is anomalous. The use of the Kriging process is particularly advantageous because Kriging automatically provides an error for an interpolated value, which is utilized in the present invention and which is not readily available with other interpolation methods without additional processing.
Other technical advantages are readily apparent to one skilled in the art from the following figures, descriptions, and claims.